The present invention relates to a filler detection method and a filler detection device which each detect a filling status of a concrete filled to a form formed with a precast concrete, for example.
In a structure of a building, by convention, reinforcing bars are arranged in a form formed with precast concrete (referred to as a “precast concrete form”), and concrete is filled or poured into the precast concrete form.
Recently, with the trend of design diversification, the precast concrete form is also complicated in shape. In this situation, the market needs a technical method which is capable of non-destructively inspecting if concrete satisfactorily reaches the distal regions of the complicatedly shaped form.
Examples of such non-destructive inspection methods, currently commercialized, are JP-A-07-269120 (Japanese Application Publication Number: Hei07-269120), JP-A-10-197467 (Japanese Application Publication Number: Hei10-197467) and JP-B2-2836799, (Japanese Patent Registration Number: 2836799). In each of those technical methods, two electrodes are disposed within the precast concrete form. When concrete contacts with those two electrodes, an electric potential appears between those electrodes. The filling of concrete is detected on the basis of the detected electric potential.
In addition to those three methods, another technique exists. In the technique, a thermocouple is located in the precast concrete form. A status of the filling of concrete is detected based on a temperature variation by the utilization of a difference between the specific heat of air and that of concrete.
Those conventional concrete filler detection methods have the following problems.
In the technique in which the electrodes are located within the precast concrete form, an electric potential between the electrodes is affected by the hardness of water contained in the concrete and ambient temperature, and is not fixed in value. Accordingly, it is necessary to set up a reference value of the electric potential in a building site each and every time. In this respect, the working efficiency is not good.
The conventional technique, which detects a filling status of concrete by utilizing the specific heat difference between air and concrete, cannot detect accurately the concrete filling status when a temperature difference between the concrete and air is small. Particularly, in the case of a building structure built in the sea, the interior of it is filled with seawater. Therefore, it is difficult to detect the filling status based on the temperature difference.
Any of the conventional techniques cannot distinguish between mortar and concrete containing the aggregate. Because, the filling status detecting systems, currently commercialized, are both designed to detect the filling status by utilizing chemical properties of the mortar, and the concrete is different from the mortar in that the former contains the aggregate, and hence, if the system cannot recognize the presence of the aggregate, it cannot distinguish between the concrete and the mortar.